Electrochemical apparatus with barrier layer protected substrate

ABSTRACT

The present invention relates to apparatus, compositions and methods of fabricating high performance thin-film batteries on metallic substrates, polymeric substrates, or doped or undoped silicon substrates by fabricating an appropriate barrier layer composed, for example, of barrier sublayers between the substrate and the battery part of the present invention thereby separating these two parts chemically during the entire battery fabrication process as well as during any operation and storage of the electrochemical apparatus during its entire lifetime. In a preferred embodiment of the present invention thin-film batteries fabricated onto a thin, flexible stainless steel foil substrate using an appropriate barrier layer that is composed of barrier sublayers have uncompromised electrochemical performance compared to thin-film batteries fabricated onto ceramic substrates when using a 700° C. post-deposition anneal process for a LiCoO 2  positive cathode.

RELATED APPLICATIONS

The present application is a continuation, and claims the benefit under35 U.S.C. §120, of U.S. patent application Ser. No. 11/374,282,converted from U.S. provisional application Ser. No. 60/690,697, andfiled on Jun. 15, 2005, entitled “Electrochemical Apparatus with BarrierLayer Protected Substrate,” which is a continuation-in-part, and claimsthe benefit under 35 U.S.C. §120, of U.S. patent application Ser. No.10/215,190, filed 9 Aug. 2002, entitled “Methods of and device forencapsulation and termination of electronic devices,” now U.S. Pat. No.6,916,679, issued 12 Jul. 2005, which are incorporated herein byreference.

FIELD OF THE INVEfNTION

The field of this invention is the apparatus, composition, andfabrication of lithium-based, solid-state, thin-film, secondary andprimary batteries with improved capacity density, energy density, andpower density, and preferably with flexible form factor and crystallineLiCoO₂, LiNiO₂, LiMn₂O₄ cathodes and derivative materials.

BACKGROUND OF THE INVENTION

The following passage describes the need and evolution of the subjecttechnology in the field of thin film batteries.

Thin-film batteries may be fabricated by sequential vacuum depositionsof layered battery components onto a given substrate in, for example,the following order: positive cathode current collector, positivecathode, negative anode current collector, electrolyte (separator),negative anode, and encapsulation. A lamination process may be usedinstead of a deposition process step (see, for example, U.S. Pat. No.6,916,679 versus Wang et al., 143 J. Electrochem. Soc. 3203-13 (1996) orU.S. Pat. No. 5,561,004). Optionally, the two terminals of a thin-filmbattery may not simply comprise extensions of the positive and thenegative current collectors, but may be additionally deposited terminalcontacts that make electrical contact to the respective currentcollector. The positive cathode material may be insufficientlycrystalline in the as-deposited state and, associated with this fact,may exhibit insufficient electrochemical properties (see, for example,Wang et al., supra). For this reason, the positive cathode may becrystallized during battery fabrication, which can be achieved in apost-deposition, high-temperature (“anneal”) process (see, for example,Wang et al., supra or Bates et al., “Thin-Film Lithium Batteries” in NewTrends in Electrochemical Technology: Energy Storage Systems forElectronics (T. Osaka & M. Datta eds., Gordon and Breach 2000)). Theanneal process, which is applied immediately after the deposition of thepositive cathode, may limit the choice of materials for the substrateand positive cathode current collector, thereby limiting, in turn, thecapacity density, energy density, and power density of the thin-filmbattery, both per volume and weight. The affect of the substrate onthose three quantities is, for example, explained in more detail below.

The intrinsic (i.e., without substrate and without encapsulation)volumetric and gravimetric densities of the capacity, the energy, andthe power of lithium-based, solid-state, thin-film secondary(rechargeable) and primary (non-rechargeable) batteries are dominated bythe volumetric and gravimetric densities of the capacity, the energy,and the power of the positive cathode material. Crystalline LiCoO₂ maybe an example of a choice for the positive cathode material for bothbulk (non thin-film) and thin-film batteries in terms of volumetric andgravimetric densities of the capacity, energy, power, and cyclability,in the case of secondary batteries, followed by derivatives ofcrystalline LiMn₂O₄, crystalline LiMnO₂, and crystalline LiNiO₂. Dopingthese main parent positive cathode materials with other transitionmetals (leading to derivatives) such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni,Cu, Zn, Y, Zr, Nb, Mo, Ru, Rh, La, Hf, Ta, W, and Re and main groupelements selected from the groups 1, 2, 13, 14, 15, 16 and 17 has beenfound to alter the properties of LiCoO₂, LiMn₂O₄, LiMnO₂, and LiNiO₂with only little, if any, overall improvement.

According to U.S. Pat. No. 6,280,875, native titanium oxide on a Tisubstrate is not inert enough to prevent adverse reactions fromoccurring between a Ti substrate and the battery components. Thisapproach is severely restricted because the choice of substratematerials is limited to materials capable of forming a native surfaceoxide during the anneal step of the positive cathode. Apart from thepresent invention, metallic substrates including flexible foils that donot form a native surface oxide have not been employed successfully asthin-film battery substrates. Fabricating solid-state, thin-filmsecondary batteries by depositing, for example, high-temperature cathodematerials directly onto metallic substrates, including flexible foils,other than Zr, and then annealing at high temperature, such as 700° C.in air for 1 hour, may result in the positive cathode and substratematerials reacting detrimentally to such an extent that the positivecathode is rendered useless. Pure Ti and Zr substrates are alsorelatively expensive.

Prior thin-film batteries do not disclose the use of an effectivebarrier layer between the substrate and the battery, and, therefore,provide potential negative observations. A need exists for the presentinvention such as, for example, an inventive barrier layer withsublayering attributes to overcome certain problems of prior thinfilm-batteries.

SUMMARY OF THE INVENTION

Various aspects and embodiments of the present invention, as describedin more detail and by example below, address certain of the shortfallsof the background technology and emerging needs in the relevantindustries.

The number of portable and on-board devices continues to increaserapidly while the physical dimensions available may decrease. Thebatteries that run these devices should keep pace with the demands ofthe devices served, potentially shrinking in size while, for example,delivering the same power. The thinner the batteries become, the moreapplications they may serve. One enabling power device is the thin-film,solid-state battery. When footprint is a limiting factor but capacitydemand is still “high,” it becomes important to pack and stack as manybattery cells as possible into the space (footprint×height) available.

The batteries with the highest capacity, voltage, current, power, andrechargeable cycle life may, for example, take advantage of today's mostpowerful positive cathode materials, LiCoO₂, LiMn₂O₄, LiMnO₂, LiNiO₂,and derivatives thereof.

When vacuum deposited into thin-films, these materials may preferablyinclude post-deposition annealing at high temperatures in order toimprove their crystallinity, which is directly related to development oftheir full range of electrochemical properties. For an electrochemicalapparatus, which employs such a thin-film battery, to become thinner,mainly the inert, electrochemically inactive part of the electrochemicalapparatus should become thinner. One approach may be to build thebattery on thin, metal foil substrates instead of thick, bulky ceramicones. Metal foils are more flexible, thinner, and less expensive thanceramic substrates of the same footprint. Furthermore, they are easilyavailable in much larger areas which translates into substantial costsavings in manufacturing.

However, LiCoO₂, like other positive cathode materials, is a strongoxidizer and possesses very mobile and thus reactive lithium ions. Atthe high annealing temperatures necessary to crystallize theas-deposited LiCoO₂ film, it reacts strongly with most metals and alloysas well as with many compounds, except for a limited number of inertceramics. In other cases, unwanted species from the substrate maydiffuse into LiCoO₂ during the high annealing temperatures andcontaminate the positive cathode, thereby detrimentally altering itselectrochemical properties. If the annealing temperature is keptsufficiently low to prevent reactions or unwanted diffusion, then thepositive cathode may not fully crystallize, and capacity, energy,current, and power capability, and, in the case of rechargeablebatteries, lifetime (number of cycles) may suffer.

High-power positive cathode materials may unfold their full, desirable,electrochemical properties in their crystalline state. Because thesematerials may, for example, be used in the present invention inthin-film form, they may typically be deposited by one of the commonvapor phase thin-film deposition methods, such as sputter deposition(RF, pulse DC, or AC), electron-beam evaporation, chemical vapordeposition, plasma enhanced chemical vapor deposition, spray pyrolysis,ion-assisted beam evaporation, electron-beam directed vapor deposition,cathodic arc deposition, etc. These vapor phase methods may not producepositive cathode films in the as-deposited state that exhibit comparableelectrochemical properties to positive cathodes that are fabricated fromtheir respective, well-crystallized powders used in bulk batteries, suchas cell phone and camcorder type batteries. Thus, the inferiorelectrochemical properties of such positive cathodes deposited bythin-film methods may be attributed to the lack of the necessary degreeof crystallinity in the as-deposited state.

The degree of crystallinity, however, may be improved by apost-deposition anneal at higher temperatures, typically between 200°C.-900° C., better between 500° C.-850° C., and even better between 650°C.-800° C. Atmospheres used in these anneals are typically air, O₂, N₂,Ar, He, H₂, H₂O, CO₂, vacuum (P<1 Torr), or mixtures thereof. To achievesufficient Zcrystallization and hence improved electrochemicalproperties, annealing times should preferably, for example, be extendedwhen reducing the annealing temperature below about 650° C. The rate ofcrystallization may be exponentially activated by temperature, and thusdecreases significantly with decreased annealing temperature. If theanneal temperature is lowered too much, then the applied energy from theannealing temperature may not be sufficient to overcome the thermalactivation energy necessary for the crystallization process to occur atall. For example, a 900° C. anneal in air for 15 minutes may yield thesame degree of crystallinity in magnetron-sputtered LiCoO₂ films asabout a 1 hour anneal in air at 700° C. and as about a 12 hour anneal inair at 600° C. After annealing at 400° C. in air for 24 hours, theelectrochemical quality of magnetron-sputter-deposited LiCoO₂ cathodefilms may remain poor and unimproved after 72 hours at that temperature.Thus, LiCoO₂ cathode films fabricated via vapor phase methods may bepost-deposition annealed at 700° C. in air for about 30 minutes to 2hours. This relatively high annealing temperature, however, may causechemical compatibility issues, thereby rendering such an annealing steppotentially undesirable in the fabrication process of thin-filmbatteries, as well as increasing the cost and reducing the fabricationthroughput.

Post-deposition annealing conditions may severely limit the choice ofsubstrate materials. Not only should substrates preferably be able towithstand the high annealing temperatures (T>500° C.), but they shouldalso preferably be chemically inert against all battery film materialsthat are in contact with the substrate with regards to the annealatmosphere, battery operation, and storage conditions applied. Likewise,the substrate should preferably not be a source of impurities that candiffuse into the battery film materials, neither during fabrication northereafter during operation and storage of the electrochemicalapparatus. Such impurities may poison any of the battery film materialsand diminish, severely impact or even destroy battery performance andlifetime. Certain choices of substrates may be, for example, restrictedto chemically inert, high-temperature ceramics, for example, Al₂O₃, MgO,NaCl, SiC, and quartz glass. Two metals, Zr and Ti, for example, havedemonstrated limited success as metallic substrates. The electrochemicalapparatus of the present invention does not require the substrate to beZr or Ti.

Although the above-mentioned ceramics have demonstrated their ability towithstand high temperatures without chemical reactions during thethin-film battery fabrication, there may be significant drawbacks tousing them in cost-effective manufacturing of thin-film batteries.Ceramics tend to be at least 5 mil≈125 μm thick, brittle, inflexible(rigid), and relatively expensive per given footprint. Also, their sheerarea size may be limited. The thinner the ceramic substrate becomes, thesmaller the maximum area that can safely be handled without breaking theceramics. For example, 12 inch×12 inch plates of ¼ inch thick Al₂O₃ arecommercially readily available. However, thinned and polished Al₂O₃ceramic substrates of 10 mil≈250 μm in thickness reduce the area thatcan be fabricated with reasonable yields to approximately 4 inch×4 inchboards. Thin (<20 mil or <500 μm), 4 inch×8 inch polished ceramic boardsare available as custom orders, but not as a routinely stocked item atacceptable prices for large-scale manufacturing of thin-film batteries.

Due to their fragile character below about 100 μm, the use of ceramicsas a substrate material for thin-film batteries may become impractical(despite the discussion in U.S. Pat. No. 6,632,563, discussing Micasubstrates with thicknesses below 100 μm). One of the properties of Micais its extremely brittle and fragile character, even at much greaterthicknesses than 100 μm. Using ceramic substrates thicker than 100 μm,however, may cause the electrochemically inactive mass and volume of thesubstrate to make up more than 90% of the total battery weight andvolume, which may be undesirable.

For all of these stated reasons, non-ceramic foils may be used asthin-film battery substrates. Under non-ceramic substrates, including,for example, metallic and polymeric substrates, silicon, and dopedsilicon may assume an intermediate position.

Non-ceramic foils, for example, may offer advantages as substrates forthin-film batteries, provided the substrate material is able towithstand the processing conditions, including temperature and, forexample, contacting certain potentially reactive battery layers.Relative to ceramic substrates of a given footprint, non-ceramic foilsubstrates can be thinner, more flexible, less expensive, readilyavailable in larger sizes, and may decrease the overall thickness of thebattery or electrochemical apparatus while reducing theelectrochemically inactive mass and volume of the entire battery, whichin turn may increase the battery's capacity density, energy density, andpower density. Non-ceramic foils are, for example, available in rolls of0.5-5 mil≈12-125 μm thickness, up to several meters wide, and up to manymeters in length. Substrates that come in long rolls present thepossibility of roll-to-roll fabrication at much lower costs than thetypical batch mode fabrication processes currently in practice.Fabricating a thin-film battery on a thinner, more flexible substratewithout compromising battery performance, compared to a thin-filmbattery fabricated on a thick rigid substrate, plays a role in enablingcertain applications for the thin-film battery technology.

Reducing the electrochemically inactive mass and volume of the batteryby making the substrate significantly thinner may increase the capacitydensity, energy density, and power density of the battery per mass andvolume. For example, a given application may allot a volume for thebattery of 2 cm×2 cm×0.1 cm. Currently, there are no traditional buttoncell or jelly roll (spiral wound or prismatic) batteries available thatcan physically fit in that volume. In contrast, a thin-film, solid-statebattery may fit that volume because even when fabricated onto a ceramicsubstrate of 0.05 cm, the entire battery, including an optionallyprotective encapsulation or encasing (see definitions further below), ismuch thinner than 0.1 cm. Fabricating a thin-film battery on a 2 mil≈50μm=0.005 cm thick foil substrate with the same footprint and samebattery capacity may further allow the stacking of a maximum of 20batteries into this volume. The actual number of batteries isdetermined, for example, by the thickness of each battery cell includingits substrate and its optional, protective encapsulation or encasing.Using a thin non-ceramic foil substrate instead of a thick ceramic onemay cause a manifold increase in capacity density, energy density, andpower density.

Thin-film batteries may, for example, be fabricated by sequentiallydepositing the individual battery component layers on top of each other.As mentioned, examples of the best positive cathodes include (but arenot limited to) LiCoO₂, LiMn₂O₄, LiMnO₂, LiNiO₂, and derivates thereof.The electrochemical apparatus of the present invention does not requirea Li_(x)V₂O_(y) cathode where 0<x≦100 and 0<y≦5. The positive cathodesmay include a post-deposition anneal at temperatures well above 500° C.in order to crystallize completely, thereby achieving their fullelectrochemical properties. Because certain known solid-state lithiumelectrolytes may react destructively when in contact with thehigh-temperature positive cathodes at these high temperatures, thepositive cathode can be deposited and annealed before depositing theelectrolyte layer.

Positive cathode materials may generally be considered poorsemi-conductors, at least over some range of their state of chargeduring battery operation. To get maximum power out of the battery andinto the external circuit, the positive cathode layer may be depositedonto a metallic back contact, the cathode current collector (CCC) layer.This CCC also should undergo the high-temperature cathode anneal and notreact with the positive cathode at the same time. For this reason, anoble metal such as, for example, gold or an alloy thereof, orequivalent may be used.

The facts outlined above suggest that for improvement in the performanceof batteries, positive cathode materials may be deposited as the secondlayer of batteries immediately after the deposition of the CCC. Thepost-deposition anneal of the positive cathode layer may, therefore,accomplish its crystallization before the next fabrication step, theelectrolyte deposition. Due to the close proximity of thehigh-temperature cathode material to the substrate, which may only beseparated from each other by a relatively thin CCC (0.1-1 μm), strongdetrimental interdiffusion and reaction of the positive cathode and thesubstrate have been observed when not using ceramic substrates, butinstead high-temperature stable metallic foils, such as stainless steel.This interdiffusion may, for example, not be blocked out by the metallicCCC itself for three main reasons. First, the CCC film is relativelythin (0.1-1 μm), thereby representing only a thin pseudo-diffusionbarrier. Second, the CCC exhibits a crystalline grain structure. Grainboundaries may be the usual locations for ionic and electronic diffusionand conduction so that the CCC should be viewed as inherently permeablefor ions and electrons from both the adjacent positive cathode layer andthe adjacent metallic foil substrate. Thus, during the cathode annealstep, the foil substrate material and cathode film material mayinterdiffuse. Third, the metallic CCC alloys directly into the metallicfoil substrate affecting its current collecting properties.

The thickness of the CCC is determined, for example, by cost, mass,volume, and adhesion, which all may become technologically impracticalwhen fabricating the CCC thicker than about 2 μm, especially when usinga costly noble metal such as gold. Potentially, significantly thickerCCC films of about more than 5 μm may avoid interdiffusion depending,for example, on temperature and pertinent dwell time of the annealingstep. However, the use of such a thick CCC may, for example, incorporateincreased materials costs and potentially unreliable adhesion.

Replacing ceramic substrates with metal foil substrates introducestremendous opportunities for enabling new technologies using thin-filmbatteries, in addition to reducing fabrication costs over thin-filmbatteries fabricated onto ceramic substrates. In contrast to ceramicplates, metallic foils are commercially readily available in thicknessesof less than 75 μm with some materials available as thin as 4 μm. Thesefoils are much more flexible than their ceramic counterparts, contributeless structural, inactive mass to the battery, and, most importantly,substantially reduce the overall thickness of the complete thin-filmbattery device. It should be emphasized that minimizing the overallthickness and increasing the flexibility of the battery is criticallyimportant for most thin-film battery applications. Thinner thin-filmbattery devices are able to fit into new, physically smallerapplications. What was once not practical with a button-cell battery nowbecomes possible with a thin-film battery (i.e., smart cards, etc.). Theadded flexibility of a foil substrate further, for example, allowsconformation to new, non-planar shapes.

Furthermore, thin metal foils may generally cost less than ceramics perfootprint area and come in much larger sizes such as rolls. With theavailability of flexible, large area substrates, the potential existsfor developing roll-to-roll fabrication methods, thereby furtherreducing production costs.

New applications may, for example, be enabled with a thin-film batterythat provides uncompromised or improved performance relative tostate-of-the-art thin-film battery that is fabricated on ceramicsubstrate. In this regard, the present invention may include thedeposition of an interdiffusion barrier layer onto metallic foilsubstrates wherein the barrier layer chemically separates the battery(i.e., electrochemically active cell) part from the substrate part ofthe electrochemical apparatus during high and low post-deposition annealtemperatures, for example, in the range between 100° C. and up to themelting point of the substrate, aswell as all operation and storageconditions of the electrochemical apparatus while not becoming a sourceof impurities itself. An embodiment of this aspect of the presentinvention is shown, for example, in FIG. 1.

The barrier may, for example, prevent diffusion of any contaminantsentering the battery from the substrate as well as, for example, blockions from escaping the battery and diffusing into the substrate duringboth battery fabrication and during battery operating and storageconditions. Such a barrier layer may not, for example, exhibit a grainstructure at any time. That is, it may be amorphous or glassy in itsas-deposited state and remain as such throughout the entire annealingand battery fabrication process as well as during battery operation andstorage conditions. The absence of a grain structure in the barrierlayer may avoid the detrimental grain boundary diffusion or conductionof ions and electrons. As mentioned earlier, grain boundaries are thepathways along which impurities and contaminants may travel. Whencertain of these conditions are met, the thin-film batteries fabricatedon metallic substrates, flexible and thin or less flexible and thicker,may exhibit properties comparable to, for example, thin-film batteriesfabricated on chemically inert yet thick, heavier, rigid, and expensiveceramic substrates.

Certain potentially suitable materials for the diffusion barrier layermay be poor ion conducting materials, for example, such as borides,carbides, diamond, diamond-like carbon, silicides, nitrides, phosphides,oxides, fluorides, chlorides, bromides, iodides, and any multinarycompounds thereof. Of those compounds, electrically insulating materialsmay further prevent possible reactions between the substrate and thebattery layers to occur, because for example, if these chemicalreactions may include the diffusion of ions and electrons, then blockingelectrons is one means of blocking these example chemical reactions.However, electrically conducting materials may be used as well, forexample, ZrN, as long as they are, for example, not conducting any ofthe ions of the substrate or battery layer materials. In some casesmetals, alloys, and/or semi-metals may serve as a sufficient barrierlayer depending on the anneal temperatures applied during the batteryfabrication process and substrate material used. The diffusion barrierlayer may, for example, be single or multi-phase, crystalline, glassy,amorphous or any mixture thereof, although glassy and amorphousstructures are usually used due to their lack of grain boundaries thatwould otherwise serve as locations for increased, but unwanted, ion andelectron conduction.

Because certain materials block out the conduction of a wide variety ofions, they may also be used in certain non-lithium containing thin-filmbatteries, such as batteries whose electro-active ions are, for example,beryllium, sodium, magnesium, potassium, calcium, boron, and aluminum.The thickness of the diffusion barrier layer may, for example, rangefrom 0.01 μm to 1 mm.

Although the barrier and/or sub-barrier layer concepts and principlesfor thin-film batteries of the present invention have initially beendeveloped for metallic substrates, the same barrier layer materials may,for example, be deposited onto polymeric substrates and doped andundoped silicon substrates whose associated thin-film batteryapplications are also of commercial interest. The post-deposition annealtemperatures may, for example, be lower than the melting point of thesilicon or polymeric substrates used, irrespective of the barrier layerapplied in order to, for example, avoid melting of the substrate.

An embodiment of the present invention relates, for example, to a methodfor fabricating flexible, high-capacity, solid-state, thin-filmbatteries on thin foil substrates, for example, metallic substrates. Forthe purpose of the present invention, an electrochemical apparatus isdefined as an apparatus comprising at least one electrochemical activecell, for example a thin-film battery, a pertinent substrate, forexample a metallic substrate, and a suitable diffusion barrier layer,which in turn can be composed of a multitude of barrier sublayers,between the electrochemically active cell and the substrate (see FIG.1). In addition, the electrochemical apparatus may include a protectiveencapsulation or protective encasing, as will be discussed furtherbelow.

The success of certain embodiments of the present invention isattributed to the utilization of an appropriate, chemically inertdiffusion barrier layer and sublayers between the substrate and thethin-film battery which may effectively separate these two parts of theelectrochemical apparatus. The diffusion barrier layer can, preferably,be able to withstand the high annealing temperatures that may be appliedto the thin-film battery part during its fabrication onto the substrate,be chemically inert to both the substrate and the thin-film batterypart, not be a source of impurities, at least not for the thin-filmbattery part, and keep the thin-film battery part chemically separatedfrom the substrate under the operating and storage conditions of theelectrochemical apparatus after its completed fabrication. Additionally,the barrier layer should for example, preferably, prevent diffusion ofany contaminants attempting to enter the thin-film battery part from thesubstrate, as well as block Li ions from escaping the thin-film batterypart and diffusing into the substrate during both battery fabricationand all battery operating and storage conditions. As an added benefit,the barrier layer may also protect the substrate during processing fromthe atmosphere applied during the post-deposition anneal and from any ofthe thin-film battery components already present at that fabricationstage of the unfinished electrochemical apparatus.

Fabricating the diffusion barrier of a multitude of barrier sublayersallows the fine-tuning of the physical (mechanical (in particular,pinhole-freeness, flexibility, and adhesion), electrical, magnetic,acoustic, thermal, and optical) and chemical properties of the diffusionbarrier layer and thus improves the performance and reliability of theelectrochemical apparatus over one that is fabricated with a diffusionbarrier layer that might include only one single layer of a givenmaterial, such as Si₃N₄, for example, or Ti₈₄B₁₆, for example, whichthermodynamically is a two-phase system (“composite”) of almost equalamounts of TiB₂ and beta-B (see Binary Alloy Phase Diagrams, 2^(nd) Ed.(T. B. Massalski, H. Okamoto, P. R. Subramanian, and L. Kacprzak eds.,ASM International 1990), incorporated herein by reference), or a TiO₂—Ba_(0.5)Sr_(0.5)TiO₃ composite material, such as described in U.S. Pat.No. 6,444,336 (incorporated herein by reference). In the simplest form,a diffusion barrier layer of the present invention may include a thin(˜1000 Å) barrier sublayer with additional adhesion improvingproperties, such as Ti, and one (1 μm) thicker barrier sublayer, such asSi₃N₄.

Barrier sublayer materials for a diffusion barrier layer of the presentinvention may include, but are not limited to, thin-films of amorphousSi₃N₄, SiC, ZrN, and TiC, among others. These are exemplary of compoundswhich may effectively serve as barriers due to their ion blockingproperties, amorphous structure, and chemical inertness to thesubstrate, as well as to the battery part of the electrochemicalapparatus. The pre-eminent characteristics of these barrier layerchemistries are their inherent ability to retain their amorphous,as-deposited state and their diffusion blocking properties up tosubstantially high temperatures, for example 700° C., and for longerperiods at those temperatures, for example 2 hours, during the preferredLiCoO₂ crystallization post-deposition anneal process. As a result,thin-film batteries fabricated on metal foils with such barrier layersretain good electrochemical properties for equivalently configuredthin-film batteries that are fabricated onto ceramic substrates, butwith the added benefits of being flexible, much thinner, and cheaper.

An embodiment of the present invention further, for example, relates tofabricating an appropriate barrier layer onto substrates in conjunctionwith a subsequent thin-film battery fabrication where the barrier layermay chemically separate the substrate from the battery part during thebattery fabrication as well as during battery operation and storageconditions thereafter. Polymeric substrates and doped and undopedsilicon substrates may be used in addition to metallic substrates.

An object of an embodiment of the present invention is to provide, forexample, an electrochemical apparatus with a metallic, polymeric, ordoped or undoped silicon substrate, with a battery (electrochemicallyactive cell) on only one side of the substrate.

Another object of an embodiment of the present invention is to provide,for example, an electrochemical apparatus with a metallic, polymeric, ordoped or undoped silicon substrate, with two batteries (twoelectrochemically active cells), one on each side of the substrate.

Another object of an embodiment of the present invention is to provide,for example, a method of fabricating an electrochemical apparatus with ametallic, polymeric, or doped or undoped silicon substrate, with abattery (electrochemically active cell) on only one side of thesubstrate.

A further object of an embodiment of the present invention is toprovide, for example, a method of fabricating an electrochemicalapparatus with a metallic, polymeric, or doped or undoped siliconsubstrate, with two batteries (two electrochemically active cells), oneon each side of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary schematic of an embodiment of a chemicalseparation of the substrate part from the electrochemically active cellpart of the electrochemical apparatus via a barrier layer, whichincludes a multitude of barrier sublayers.

FIG. 2 illustrates a schematic of an exemplary use of an embodiment of abarrier layer that includes barrier sublayers of different areadimensions and provides the electrical separation between the positiveand negative part of the electrochemically active cell.

FIG. 3 a illustrates a schematic of an exemplary use of an embodiment ofa barrier layer that includes an electrically conductive barriersublayer for the case in which the electrical separation between thepositive and the negative part of the electrochemically active cell isaccomplished through fabrication of the negative part entirely on top ofthe electrolyte.

FIG. 3 b illustrates a schematic of another exemplary use of anembodiment of a barrier layer that includes an electrically conductivebarrier sublayer on metallic substrate for the case in which theelectrical separation between the positive and the negative part of thebattery is accomplished through fabrication of the negative partentirely on top of the electrolyte.

FIG. 3 c illustrates a schematic of an exemplary use of an embodiment ofa barrier layer that includes an electrically conductive barriersublayer on metallic substrate for the case in which the electricalseparation between the positive and the negative part of the battery isaccomplished through fabrication of the positive part entirely on top ofthe electrolyte.

FIG. 4 a illustrates a schematic of an exemplary use of an embodiment ofa barrier layer that includes electrically conductive barrier sublayersfor the case in which the electrical separation between the positive andthe negative part of the electrochemical active cell is not done viafabrication of the negative part entirely on top of the electrolyte.

FIG. 4 b illustrates a schematic of another exemplary use of anembodiment of a barrier layer that includes electrically conductivebarrier sublayers for the case in which the electrical separationbetween the positive and the negative part of the electrochemicallyactive cell is not done via fabrication of the negative part entirely ontop of the electrolyte.

FIG. 4 c illustrates a schematic of another exemplary use of anembodiment of a barrier layer that includes electrically conductivebarrier sublayers for the case in which the electrical separationbetween the positive and the negative part of the electrochemicallyactive cell is not done via fabrication of the negative part entirely ontop of the electrolyte while the negative anode has direct contact to abarrier sublayer.

FIG. 5 illustrates a graph of an X-ray diffraction (XRD) pattern of anembodiment of a 1.6 μm thick LiCoO₂ positive cathode film fabricatedonto 3000 Å Au cathode current collector over 300 Å Co adhesion layerattached to an electrically insulating barrier layer composed of twobarrier sublayers, 5000 Å Al₂O₃ and 6000 Å CO₃O₄, on 50 μm thickstainless steel foil type 430 substrate.

FIG. 6 illustrates a graph of an X-ray diffraction (XRD) pattern of anembodiment of a 1.6 μm thick LiCoO₂ positive cathode film fabricatedonto 3000 Å Au cathode current collector over 300 Å Co adhesion layerover a barrier layer composed of two sublayers, 5000 Å Si₃N₄ and 5000 ÅSiO₂, on 300 μm thick silicon substrate.

FIG. 7 a illustrates a schematic of an embodiment of an anodeconfiguration of the “normal configuration” in which the negative anodeis not in direct contact with the barrier layer.

FIG. 7 b illustrates a schematic of an embodiment of an anodeconfiguration of the “normal configuration” in which the negative anodeis in direct contact with at least one of the barrier sublayers.

FIG. 8 illustrates a schematic of an embodiment of an anodeconfiguration of the “normal configuration” in which the negative anodeis in direct contact with an electrically conductive ZrN barriersublayer that also serves as the anode current collector.

FIG. 9 illustrates a schematic of an embodiment of a batteryconfiguration in which the negative anode is in direct contact with thesubstrate, in case the substrate is chemically inert to the negativeanode. In this embodiment, the substrate can serve as the negative anodecurrent collector and the negative terminal, if the substrate issufficiently electrically conductive, as is the case for stainlesssteel, for example.

FIG. 10 illustrates a schematic of an embodiment of the use of amoisture protection layer to protect the moisture-sensitive electrolytelayer against moisture present in the ambient environment for the casein which the protective encapsulation has been fabricated with anopening for providing access to the negative terminal.

DETAILED DESCRIPTION OF THE INVENTION

It should be understood that this invention is not limited to theparticular methodology, protocols, etc., described herein and, as such,may vary. The terminology used herein is for the purpose of describingparticular embodiments only, and is not intended to limit the scope ofthe present invention, which is defined solely by the claims.

As used herein and in the claims, the singular forms “a,” “an,” and“the” include the plural reference unless the context clearly indicatesotherwise.

All patents and other publications identified are incorporated herein byreference in their entirety for the purpose of describing anddisclosing, for example, the methodologies, apparatuses, andcompositions described in such publications that might be used inconnection with the present invention. These publications are providedsolely for their disclosure prior to the filing date of the presentapplication. Nothing in this regard should be construed as an admissionthat the inventors are not entitled to antedate such disclosure byvirtue of prior invention or for any other reason.

Unless defined otherwise, all technical terms used herein have the samemeaning as those commonly understood to one of ordinary skill in the artto which this invention pertains. Although any known methods, devices,and materials may be used in the practice or testing of the invention,certain exemplary preferred methods, devices, and materials in thisregard are described here.

Thin-film batteries may, for example, be fabricated in batch mode bydepositing the individual battery component layers sequentially. Once asubstrate material has been selected, it may be prepared by cleaningand, if desired, other pre-treatments. The barrier layer composed of itsbarrier sublayers, which may be 0.5-5 μm thick in total, is the key tosuccessful fabrication of thin-film batteries on metallic and polymericfoils as well as silicon. The barrier layer should be able to withstandthe annealing temperatures for the positive cathode film together withthe cathode current collector, remain chemically inert, and not be asource of impurities.

Additionally, the barrier layer should prevent diffusion of anycontaminants entering the positive cathode from the substrate as well asblock all ions and atoms from the positive cathode and the cathodecurrent collector from diffusing into the substrate during both thebattery fabrication and all battery operating and storage conditions.The barrier layer may be deposited onto the clean substrate andtypically coats the substrate everywhere with a uniform, defect-freefilm. The ensuing battery layers may then be deposited sequentially inbatch fashion using shadow masks to demarcate the boundaries of eachlayer of the thin-film battery. The barrier layer may be designed andfabricated to isolate the effects of grain boundary diffusion, therebyeliminating reactions between the subsequently deposited positivecathode, such as LiCoO₂, with its underlying cathode current collectorand the substrate, such as for example a gold cathode current collectorand a flexible stainless steel foil substrate, respectively. Thefollowing presents exemplary ways of depositing embodiments of barrierlayers, including their barrier sublayers, onto substrates onto whichthin-film batteries are fabricated.

1. Substrate Selection and Preparation

First, the substrate material may be chosen. The thin-film batteries maybe fabricated on a variety of metallic foils and sheets with variedsurface finishes. A thin foil of stainless steel may be used for thesubstrate. However, other, more expensive and thicker materials or lowermelting materials work as well, including, but not limited to, Ti andTi-alloys, Al and Al-alloys, Cu and Cu-alloys, and Ni and Ni-alloys, forexample. Additionally, the preferred physical properties of the foil,such as type of steel alloy, surface roughness, homogeneity, and purity,are left to the user to determine the optimum manufacturing parametersfor the particular device. The electrochemical apparatus of the presentinvention does not require the substrate to be Al coated with metals orsemi-metals that include V, Mn, Mg, Fe, Ge, Cr, Ni, Zn, and Co.Moreover, the electrochemical apparatus of the present invention doesnot require the substrate to be a pure polymide.

Once the stainless steel foil material, for example, has been selected,it is generally cleaned in order to remove oils, particulates, and othersurface contaminants that may otherwise impede chemical or mechanicaladhesion of the barrier layer to the substrate. Any cleaning procedure,for example, any suitable wet chemical cleaning or plasma cleaningprocess that provides a sufficiently clean surface, may be used in thisregard. Optionally, the cleaned foil substrate may be furtherpre-treated, if so desired. For example, to relieve the intrinsic stressof metallic foils, an anneal step at high temperatures (e.g., 500° C.)prior to depositing the barrier layer may be employed, provided that theanneal temperature remains below the melting point of the metallic foil.

Although substantially independent of any foil material and itsthickness, several annealing strategies may further reduce oraccommodate thermal and mechanical stresses on a film-by-film basis. Forexample, pre-annealing a cleaned foil may be performed as describedabove to condition an uncoated metal foil. Additionally, other annealingsteps may include, for example, a post-deposition barrier layer anneal,a post-deposition cathode current collector layer anneal, or anycombination of post-deposition layer anneals prior to the cathodecrystallization anneal. Such steps may be preceded or followed byadditional plasma treatments (see, for example, D. M. Mattox, Handbookof Physical Vapor Deposition (PVD) Processing, Society of VacuumCoaters, Albuquerque, N. Mex. 660ff and 692ff (Noyes Publications1998)). Analogously, silicon and polymeric substrates may be prepared.

2. Barrier Layer Deposition

Depositing a barrier layer onto substrates may be performed inconjunction with thin-film battery fabrication that, for example,chemically separates the substrate from the battery part during thebattery fabrication as well as, for example, during battery operationand storage conditions thereafter.

In general, chemical reactions between potential reactants may beprevented when either their ions or their electrons are confined to eachof the reactants' space or blocked at the reactants' interface so thatpreferably no interdiffusion of these species between the potentialreactants is possible. In addition to the mere diffusion blockingproperties, the materials selected for the barrier layer and itsconstituting barrier sublayers should take into account that the barrierlayer (a) shall be able to withstand the annealing temperatures for thepositive cathode film together with the cathode current collector, (b)remain chemically inert, and (c) not be a source of impurities.

An electrically conductive material, such as ZrN, for example, thatpossesses adequate diffusion blocking properties relative to ions so asto chemically separate the substrate from the battery part in theelectrochemical apparatus, may be deposited. In this case, theconductive barrier sublayer may also serve as a current collector.Because ZrN is also stable in contact with negative anode materials, inparticular metallic lithium, it may be used as the cathode currentcollector and/or the anode current collector.

Although constructing a barrier layer with just one single layer of aspecific material is feasible in principle, for example, electricallyinsulating and metal ion blocking Si₃N₄, it has been found that abarrier layer composed of more than one suitable sublayer, in which eachsublayer provides different specific properties to the barrier layerwith the objective to fine-tune the barrier layer properties, achieveshigher fabrication yields and consequently higher reliability in batteryperformance over a given thin-film battery's lifetime. For this reason,the present invention focuses on the fabrication and provision of abarrier layer that is composed of more than just one single layer andthat preferably chemically separates the substrate from the battery partof the electrochemical apparatus while allowing the reliable fabricationof such apparatus.

2.1 Fabrication of a Barrier Layer Including Insulating BarrierSublayers

A barrier layer may be directly deposited onto the substrate. A barrierlayer composed of barrier sublayers wherein at least one barriersublayer is amorphous or glassy may be designed and fabricated to avoidor minimize grain boundary diffusion of ions and electrons, therebyreducing the diffusion of unwanted species into and out of the batterylayers during fabrication and during operation and storage conditions ofthe battery thereafter. It is preferable to prevent or minimize chemicalreactions between the battery components with the substrate.

Each of the barrier sublayers may, for example, be selected from a groupof materials that may block the diffusion of ions from a LiCoO₂ cathodelayer (lithium ions, cobalt ions, and oxygen ions), atoms and ions fromthe current collector (gold, platinum, nickel, copper, etc.), and ionsand atoms from the stainless steel substrate (iron, chromium, nickel,other heavy metals, and main group elements of the selected stainlesssteel type), although it may, for example, be sufficient to use simplyelectrically insulating materials that are inert to the substrate, thecurrent collector, and/or the positive cathode. Selecting a barrierlayer composed of sublayers that is capable of blocking ions andelectrons may be considered a preferable approach regarding obtaining asubstrate part and the battery part of the electrochemical apparatusthat may be chemically separated during fabrication and during operationand storage conditions of the electrochemical apparatus thereafter.

The group of binary borides, carbides, silicides, nitrides, phosphides,oxides, fluorides, chlorides, bromides, and iodides, as well as diamond,diamond-like carbon, high-temperature stable organic polymers, andhigh-temperature stable silicones may, for example, provide general ionblocking properties in addition to electrical insulation properties.Therefore, these materials may be used for the barrier sublayermaterials. In addition to using preferably the binary compounds of thesematerials, the barrier sublayers may, for example, be formed of anymultinary compound composed of these materials such as, but not limitedto, oxy-nitrides, carbo-borides, carbo-oxy-nitrides,silico-carbo-nitrides, and oxy-fluorides. The electrochemical apparatusof the present invention does not require the barrier layer to be a pureoxide.

The above-listed binary and multinary barrier sublayer materials may bedeposited by selecting one or more of the many suitable thin-filmdeposition methods including sputtering (RF-magnetron, AC magnetron, DCand DC pulse magnetron, diode RF or DC or AC), electron beamevaporation, thermal (resistive) evaporation, plasma enhanced chemicalvapor deposition, ion beam assisted deposition, cathodic arc deposition,electrochemical deposition, spray pyrolysis, etc. A Si₃N₄ barriersublayer, for instance, may be fabricated by utilizing a pure silicontarget that is sputtered preferably in a RF magnetron sputter systemusing an Ar—N₂ reactive plasma environment. SiC and TiC barrier sublayerfilms are usually RF magnetron sputtered from targets of the samerespective composition in an inert Ar plasma environment while theirnitrogen doped derivatives, SiC:N and TiC:N, are deposited from SiC andTiC targets, respectively, in a reactive Ar—N₂ plasma environment usingRF magnetron sputter equipment.

The formation of optimized oxy-nitrides, carbo-borides,carbo-oxy-nitrides, silico-carbo-nitrides, oxy-fluorides, and the likemay be accomplished by providing sputter gas mixtures that may containN₂, O₂, N₂O, BF₃, C₂F₆, B₂H₆, CH₄, SiH₄, etc. either alone or inaddition to an inert carrier gas, such as argon, and/or in addition toproviding the elements from a sputter target. For example, the thin-filmdeposition of titanium silico-carbo-nitride (or titanium silicon carbidenitride), Ti₃SiC₂:N, may be accomplished by RF magnetron sputtering inAr—N₂ plasma atmosphere using either a single sputter target constructedof alternating areas of TiC and SiC, in an overall area ratio of 3:1 ortwo separate sputter targets, one of TiC and the other one of SiC, thatare operated in such a way that they deposit a mixed material layerhaving a TiC/SiC ratio of 3:1 at any given time onto the same substratearea (dual target sputter deposition). The barrier-layer coatedsubstrate may or may not be post-deposition processed prior tocontinuing with the battery fabrication.

An example for a barrier sublayer material may be Si₃N₄, SiN_(x)O_(y)for 3x+2y=4, or oxide-gradiented Si₃N₄ that may reach a stoichiometry atits surface, or at both of its surfaces, of almost SiO₂, if so desired.Additionally, SiC or TiC, with or without nitrogen doping, may be usedas a barrier sublayer material.

A few specific derivatives of these materials may not be most preferableas ion blockers when used in a barrier layer without any further,suitable barrier sublayers, because they allow the diffusion of certainions in the fabrication process or during battery operating and storageconditions while exhibiting only poor insulating properties, such asnon-stoichiometric ZrO₂, non-stoichiometric YSZ (yttrium stabilizedzirconia), and non-stoichiometric LiI (lithium iodide). In contrast totheir stoichiometric counterparts, the non-stoichiometry is the mainreason why these materials are electrically conductive while allowingoxygen and lithium ion diffusion, respectively.

To, for example, fine-tune certain barrier properties, such as improvedadhesion to the substrate and/or the battery part, mechanicalflexibility, stability to adjacent layers, pinhole-freeness, electricalresistance, and chemical inertness, suitable barrier layers may beprovided that comprise barrier sublayers. For example, a barrier layeron top of a stainless steel 430 substrate may be constructed from astack of barrier sublayers of the following sequence: 500 Å SiO₂ (forimproved adhesion to the oxide-bonding stainless steel substrate)/2000 ÅSi₃N₄ (electrically insulating and diffusion blocking material towardslithium ions, cobalt ions, oxygen ions, iron ions, chromium ions, andgold atoms, for example)/1000 Å SiC:N (strongly diffusion blocking layerrelative to lithium ions, cobalt ions, oxygen ions, iron ions, chromiumions, and gold atoms)/2000 Å Si₃N₄ (electrically insulating anddiffusion blocking material towards lithium ions, cobalt ions, oxygenions, iron ions, chromium ions, and gold atoms, for example)/500 Å SiO₂(adhesion facilitator to the current collector layer) onto which 300 Åcobalt current collector adhesion layer and 3000 Å gold currentcollector can be deposited.

In some cases the insulating barrier sublayers may not only be incontact with the positive cathode and/or the cathode current collectorbut also may be in contact with the negative anode and/or the anodecurrent collector. In any case the barrier sublayers may, for example,be preferably chemically inert to all materials with which it is incontact. This characteristic may limit, for example, the use of a pureAl₂O₃ or SiO₂ barrier layers when in contact with a metallic lithiumnegative anode which otherwise might react detrimentally to Li₂O,LiAlO₂, and Li—Al alloys or Li₂O, Li₂SiO₃, and Li—Si alloys.

2.2 Fabrication of a Barrier Layer of at least One ElectricallyConductive Barrier Sublayer

Conductive barrier sublayers may, for example, be equally effective if,for example, they satisfy the preferable attributes of: 1) preventingionic diffusion into or out of the battery layers; and 2) not reactingwith either the substrate or the battery layers during the fabricationprocess and thereafter during all battery operating and storageconditions. The barrier layer, may, for example, include electricallyinsulating barrier sublayers as well. Such electrically insulating andelectrically conductive sublayers may, for example, not all have thesame shape or area size. Therefore, a barrier layer of such a mixedstack of barrier sublayers may, for example, be electrically conductivein some areas that are in contact with the substrate part or the batterypart while in other contact areas with the substrate part or the batterypart the barrier layer exhibits electrically insulating properties.

The materials for the electrically conductive barrier sublayers may, forexample, be selected from the group of conductive binary borides,carbides, silicides, nitrides, phosphides, and oxides, as well as fromthe group of any of their conductive multinary compounds, for example,but not limited to, oxy-nitrides, carbo-borides, carbo-oxy-nitrides,silico-carbo-nitrides, and oxy-fluorides. Also, high-temperature stablepolymers and high-temperature stable silicones may be used that arespecifically engineered to be electrically conductive. The materialsselection list for the electrically insulating barrier sublayers hasbeen provided in the previous section 2.1 above and are incorporatedherein. The barrier sublayers may be formed from completely differentcompositions, such as a barrier layer that may be fabricated of abarrier sublayer stack of, for example, 5000 Å ZrN/4000 Å Si₃N₄/3000 ÅWC/1000 Å MoSi₂ where each of the barrier sublayers may, for example,have different area dimensions.

As a result, for example, the Si₃N₄ barrier sublayer may extend over theentire footprint area of, for example, the metallic substrate while theZrN barrier sublayer only covers the area on the substrate underneaththe cathode current collector while the WC and MoSi₂ barrier sublayersare, for example, covering at least the entire area underneath the anodecurrent collector while further extending into the area of ZrN. Due toits area size, the interposed Si₃N₄ barrier sublayer may, for example,provide electrical separation of the electrically conductive ZrN barriersublayer from the electrically conductive WC/MoSi₂ barrier sublayers andthus the electrical separation between the positive and the negativeparts of the battery (see FIG. 2).

In this embodiment, an electrically conductive barrier sublayer, such asZrN, TiN, WC, MoSi₂, TiB₂, or NiP may be deposited by standarddeposition methods including sputter deposition (RF-magnetron, DC and DCpulse magnetron, AC magnetron, diode RF or DC or AC), electron beamevaporation, thermal (resistive) evaporation, plasma enhanced chemicalvapor deposition, ion beam assisted deposition, cathodic arc deposition,electrochemical deposition, spray pyrolysis, etc. onto the substrate.For example, a ZrN barrier sublayer may be fabricated either from a ZrNsputter target performing a DC magnetron sputter deposition in an inertAr atmosphere or from a metallic Zr target also using DC magnetronsputter deposition but in a reactive Ar—N₂ atmosphere.

Additionally, certain metals (e.g., Au, Pt, Ir, Os, Ag, Pd), semi-metals(e.g., graphitic carbon, Si), and alloys (e.g., based on Au, Pt, Ir, Os,Ag, Pd, C, and Si) may be selected as an electrically conductive barriersublayer, preferably, but not limited to, when the post-depositionanneal temperatures necessary to crystallize the positive cathode aremoderate, such as 200° C.-500° C. The electrically conductive barriersublayer may or may not be heat processed further before continuing withthe battery fabrication process.

If fabricated appropriately in terms of electrical accessibility fromthe positive battery terminal, a conductive barrier sublayer may havethe added advantage of eliminating a separate cathode current collector,unless, for example, one chooses to optimize the electrical propertiesof the conductive barrier sublayer by coating it with a betterconducting and inert thin layer, for example, gold. Whether or notadditionally coated with such a better conducting layer, the approach ofthe conductive barrier sublayer may include that, at the same time, theanode current collector and negative anode be separated from theconductive barrier sublayer to which the positive cathode and/or itscathode current collector makes electrical contact. This separation maybe achieved, for example, as follows:

-   -   1) By extending the electrolyte in area so that both the        negative anode and its anode current collector are entirely        located on top of the electronically insulating electrolyte,        which in turn serves, in this case, effectively as a local        barrier sublayer for the negative anode and its anode current        collector (see FIGS. 3 a and 3 b). If the specific fabrication        parameters of the positive cathode do not cause a reaction with        the already present electrolyte layer, the positive cathode and        its cathode current collector can analogously be fabricated        entirely on top of the electrolyte while the negative anode is        located underneath the electrolyte (see FIG. 3 c).    -   2) When the negative anode and/or the anode current collector        are not located entirely on top of the electrolyte, then they        may make contact with the barrier layer and thus with at least        with one of its barrier sublayers and/or the metallic substrate.        In this case, one or more of the barrier sublayers may be        electrically conductive while at least one of the sublayers        should be insulating (see FIGS. 4 a and 4 b). In any case, all        of the barrier sublayers should be chemically inert to all of        the materials with which they are in contact. This may        preferably prohibit, for instance, the use of a Pt₂Si barrier        sublayer when in contact with a negative metallic lithium anode,        because this would otherwise result in a reaction to Li_(x)Si        for 0<x<=4.4 and Li_(y)Pt for 0<y<=2 (see FIG. 4 c).        2.3 Barrier Layer and Substrates

One reason for providing a barrier layer is, for example, providingchemical separation between the substrate part and the battery part ofan electrochemical apparatus of an embodiment of the present inventionduring the fabrication of the battery part, which may entail processtemperatures of up to the melting point of the substrate, andthereafter, during all operation and storage conditions of theelectrochemical apparatus. The same principles as detailed above mayapply for at least three substrate types of the present invention, whichmay comprise metallic substrates, polymeric substrates, and doped orundoped silicon substrates.

Direct depositions of electrically insulating or conductive barriersublayers may be accomplished in a straightforward manner onto the threesubstrate types as described above. Of course, the inherent physical andchemical limitations each substrate type possesses should be observed,and the deposition parameters for each barrier sublayer should beadjusted accordingly. For example, a sputter deposition may be performedunder such high deposition rates that the resulting depositiontemperature at the substrate surface may exceed the melting point of thepolymeric substrate. Therefore, the deposition parameters shouldpreferably be limited so as to observe the melting point of thesubstrate. In another example, a very thin Si substrate of only 10 μmmay be used. In such a case, it may be relevant to adjust the stressesof the barrier sublayers during their depositions, neglecting anypost-deposition anneal for the moment, to the mechanical properties ofthe fragile Si substrate, in order not to crack it prior to thedeposition of any subsequent barrier sublayers and/or the batterylayers. More specific examples could be given without limiting the scopeof the invention with respect to the possible use of all three substratetypes and the basic principles for the fabrication of a barrier layer,including its barrier sublayers, onto them.

3. Battery Fabrication

Once the substrate in the present invention is fabricated with a barrierlayer, the subsequent fabrication steps of the electrochemical apparatusdepend on whether or not a second electrochemically active cell shall befabricated onto the second side of the substrate to accomplish a“double-sided” electrochemical apparatus, which is discussed furtherbelow. The electrochemical apparatus of the present invention does notrequire the first electrochemically active cell to be a solar battery.

For the case of a “single-sided” electrochemical apparatus, however,wherein only a first electrochemically active cell is fabricated ontothe first side of the substrate, a second layer is optionally depositedonto the second side of the substrate prior to the fabrication of thecomponent layers of the first electrochemically active cell. This secondlayer can be fabricated with the objective to protect the substrate fromthe ambient environment against chemical and mechanical factors duringthe fabrication, operation, and storage of the electrochemicalapparatus. In addition, through the implementation of the second layer,the first electrochemically active cell may be protected againstchemical contaminants from the ambient environment that could enter thesubstrate at the second, otherwise unprotected side and diffuse throughthe substrate, thereby potentially reaching and detrimentally reactingwith the first electrochemical active cell during fabrication,operation, and/or storage of the electrochemical apparatus. Thisprotection of the first electrochemically active cell may be in additionto the protection provided by the substrate itself and by the barrierlayer between the substrate and said first electrochemically activecell, in particular for the case in which the barrier layer may notcover the entire area underneath the first electrochemically activecell. The protection of both the substrate and the firstelectrochemically active cell may result in an extended lifetime of theelectrochemical apparatus.

The second layer may be fabricated from a material that includes achemical compound selected, for example, from the group of metals,semi-metals, alloys, borides, carbides, diamond, diamond-like carbon,silicides, nitrides, phosphides, oxides, fluorides, chlorides, bromides,iodides, or for example, from the group of any multinary compoundscomposed of borides, carbides, silicides, nitrides, phosphides, oxides,fluorides, chlorides, bromides, and iodides, or for example, from thegroup of high-temperature stable organic polymers and high-temperaturestable silicones. In particular, a thin metal layer, between 500 Å and 5μm thick, may be useful to protect the substrate by blocking the entryof contaminants at said second side during the fabrication, operation,and/or storage of the electrochemical apparatus. Furthermore, a metallayer, for example, nickel or titanium, may be useful because it can bedeposited relatively fast and inexpensive compared to its ceramiccounterparts, for example, TiC.

The blocking action of the second layer may, for example, include achemical reaction of the second layer with the contaminants, which isknown in the literature as chemical gettering, corrosion inhibition, orsacrificial layer provision, and is not limited to metal layers, butcould also be accomplished with, for example, sub-oxides or sub-nitrides(insufficiently oxidized or nitrided film materials that can easily befabricated by sputter depositions, for example) or, for example,nitrides or carbides that may convert into oxides or carbonates whenreacting with the oxygen, moisture, or carbon dioxide contaminantspresent in the ambient environment during the fabrication, operation,and/or storage of the electrochemical apparatus.

One may fine-tune the second layer on the second side of the substrateby selecting materials that protect either mainly without a chemicalreaction or mainly via chemical reaction. A further fine-tuning may thenoccur, for example, by selecting one of the latter materials but with ahigher or a lesser reactivity under certain ambient environmentconditions. For example, Al₄C₃ converts into Al₂O₃ at much lowertemperatures and oxygen partial pressures than SiC to SiO₂. Likewise,nitrides with a very small enthalpy of formation, such as CO₂N, convertinto the respective oxides at much lower temperatures and oxygen partialpressures than their counterparts that formed under a large negativeenthalpy of formation, such as Si₃N₄ and ZrN.

Ultimately, it is up to the manufacturer of the electrochemicalapparatus to decide on its optimum parameters relative to added costsfor the fabrication of the second layer on the second side of thesubstrate, which is mainly a function of the materials selection and thefabricated thickness of the second layer, versus added protection of thesubstrate and the first electrochemically active cell against specificambient environment conditions that exist for specific periods of time,which again is mainly a function of the materials selection and thefabricated thickness of said second layer.

Thin-film batteries may be manufactured in a batch fabrication processusing sequential physical and/or chemical vapor deposition steps usingshadow masks to build up the individual battery component layers.Electrochemically active cells may be fabricated with any of severalstructures. The features may include:

-   -   (i) the positive cathode configuration to be used        -   a. the positive cathode located between the barrier layer            and the negative anode (cathode deposition prior to anode            deposition; “normal configuration”), and the negative anode            located between barrier layer and the positive cathode            (anode deposition prior to cathode deposition; “inverted            configuration”)        -   b. the post-deposition anneal that is applied to the            positive cathode    -   (ii) the anode configuration to be used        -   a. the negative anode layer contacts or does not contact the            barrier layer        -   b. the anode current collector layer contacts or does not            contact the barrier layer    -   (iii) the type of barrier layer to be used        -   a. electrically insulating sublayers vs. electrically            conductive sublayers        -   b. area dimensions of a given sublayer in comparison to the            other sublayers in a given barrier layer        -   c. sequence combinations of insulating and conductive            sublayers in the barrier layer    -   (iv) the substrate is or is not in electrical contact with the        electrochemical active cell (either with its positive part or        with its negative part)    -   (v) the electrochemical active cell is fabricated on one side        (single-sided electrochemical apparatus) or both sides of the        substrate (double-sided electrochemical apparatus)    -   (vi) protective encapsulation or protective encasing design to        be used        -   a. encapsulation vs. encasing        -   b. opening(s) in encapsulation or encasing vs. no opening(s)            for access to terminals        -   c. use or no use of moisture protection layer in opening            area    -   (vii) current collectors and terminals.        3.1 Cathode Configuration        3.1.1 The Positive Cathode Located Between the Barrier Layer and        the Negative Anode, which may be Equivalent to the Deposition        and Potential Post-deposition Anneal of the Positive Cathode        Prior to the Deposition of the Negative Anode: “Normal        Configuration.”

Depending on the electrical properties of the barrier layer, a cathodecurrent collector may be fabricated prior to the deposition of thepositive cathode. That is, if the barrier layer based on its sublayersis insulating in the area where the positive cathode is to befabricated, then a cathode current collector may be deposited in orderto create the necessary electrical access to the positive cathode fromthe positive terminal. If, however, the barrier layer based on itssublayers is electrically conductive in the area where the positivecathode is to be deposited, then an additional inert metal layer(“conduction enhancer”) may optionally be deposited between the barrierlayer and the positive cathode in order to enhance the currentcollecting properties of the barrier layer.

The positive cathode, the cathode current collector, and the conductionenhancer of the barrier layer may be deposited by selecting any of themany deposition methods including sputtering (RF-magnetron, DC and DCpulse magnetron, AC magnetron, diode RF or DC or AC), electron beamevaporation, thermal (resistive) evaporation, plasma enhanced chemicalvapor deposition, ion beam assisted deposition, cathodic arc deposition,electrochemical deposition, spray pyrolysis, etc.

After the deposition of the positive cathode a post-deposition annealmay follow in order to improve the physical, chemical, andelectrochemical properties of the positive cathode. The most commonpost-deposition anneal occurs at 700° C. in air for about 30 minutes to2 hours which completes the crystallization of positive cathodematerials, LiCoO₂, LiMn₂O₄, LiMnO₂, LiNiO₂, and derivatives thereof.

The composition of a given derivate and the parameters of the appliedpost-deposition anneal may inform the selection of the barrier layermaterial. For example, for pure LiCoO₂ and a 700° C. anneal in air for 2hours a 3000 Å gold cathode current collector that may be attached by a300 Å cobalt adhesion layer to an electrically insulating barrier layerincluding two barrier sublayers, 5000 Å Al₂O₃ and 6000 Å CO₃O₄, on 50 μmof stainless steel 430 foil is one optional combination. The X-raydiffraction (XRD) pattern of this setup after the 700° C. anneal isshown in FIG. 5. The LiCoO₂ positive cathode exhibited a crystallitesize of about 560 Å for the (101) grains while its refined latticeparameters (a_(hex)=2.8146(4)Å; c_(hex)=14.0732(8)Å) may match thetheoretical values (e.g., ICDD 77-1370: a_(hex)=2.815(1)Å;c_(hex)=14.05(1)Å). This fact indicates that the crystalline LiCoO₂positive cathode film may not react with any of its surroundingmaterials, including the substrate, while achieving the propercrystallographic parameters that are necessary to show optimizedelectrochemical behavior in an electrochemically active cell.

Also after fabricating a pure LiCoO₂ positive cathode over 3000 Å Au/300Å Co cathode current collector attached to a barrier layer composed oftwo barrier sublayers, 5000 Å Si₃N₄ and 5000 Å SiO₂, onto 300 μm thickundoped silicon substrate followed by an anneal at 700° C. in air for 2hours, a well crystalline LiCoO₂ positive cathode (a_(hex)=2.8151(4)Å;c_(hex)=14.066(7)Å; sample grain size for the (101) plane of 1100 Å) maybe obtained with virtually theoretical lattice parameters (e.g., ICDD77-1370: a_(hex)=2.815(1)Å; c_(hex)=14.05(1)Å). Having attained a wellcrystalline, stoichiometric LiCoO₂ positive cathode film with layeredstructure and theoretical crystallographic lattice parameters provides,for example, that the crystalline LiCoO₂ positive cathode film may notreact with its surrounding materials, including the silicon substrate,as shown, for example, in FIG. 6. As with the LiCoO₂ positive cathodefilm in the previous example fabricated onto stainless steel 430 foilsubstrate, the theoretical crystallographic lattice parameters(a_(hex)=2.8151(4)Å; c_(hex)=14.066(7)Å) may suggest that a LiCoO₂positive cathode film on Si substrate may show certain preferredelectrochemical behavior.

3.1.2 The Negative Anode Located Between the Barrier Layer and thePositive Cathode, which may Provide Performance Approximating Depositionand Potential Post-deposition Anneal of the Negative Anode Prior to theDeposition of the Positive Cathode: “Inverted Configuration”.

One example of an “inverted configuration” of an embodiment of thepresent invention is schematically shown in FIG. 3 c for the case inwhich the substrate may be a metallic substrate. Depending on theelectrical properties of the barrier layer, an anode current collectormay be fabricated prior to the deposition of the negative anode. Thatis, if the barrier layer, based on its sublayers, is insulating in thearea where the negative anode is to be fabricated, then an anode currentcollector may be deposited in order to create the necessary electricalaccess to the negative anode from the negative terminal. If, however,the barrier layer based on its sublayers is electrically conductive inthe area where the negative anode is to be deposited, then an additionalinert metal layer (“conduction enhancer”) may be deposited between thebarrier layer and the negative anode in order to enhance the currentcollecting properties of the barrier layer.

The negative anode, the anode current collector, and the conductionenhancer of the barrier layer may be deposited by selecting any of themany deposition methods including sputtering (RF-magnetron, DC and DCpulse magnetron, AC magnetron, diode RF or DC or AC), electron beamevaporation, thermal (resistive) evaporation, plasma enhanced chemicalvapor deposition, ion beam assisted deposition, cathodic arc deposition,electrochemical deposition, spray pyrolysis, etc.

The negative anode may be selected from the group of metal lithium,lithium-ion anodes, and so-called lithium-free anodes (see, e.g., U.S.Pat. No. 6,168,884, incorporated herein by reference in its entirety).After the deposition of the negative anode, a post-deposition anneal mayfollow in order to improve the physical, chemical, and electrochemicalproperties of the negative anode. Preferably, such an anneal may beapplied to lithium-ion anodes, if at all, for example, to Li₄Ti₅O₁₂,but, for example, not to metallic lithium, and not preferably to a groupof lithium-free anodes.

The actual composition of the negative anode and the parameters of theapplied post-deposition anneal may inform the selection of the barrierlayer material. For example, for a metallic lithium negative anode, abarrier sublayer of 5000 Å of Si₃N₄ on silicon substrate that separatessaid silicon substrate from said metallic lithium negative anode, mayprovide the necessary barrier layer properties where the chemicalinertness between the barrier layer and the metallic lithium may beaccomplished through the positive enthalpy of reaction for the reactionpath 12Li+Si₃N₄=4Li₃N+3Si.

In an exemplary inverted configuration, the positive cathode may bedeposited onto the electrolyte. Therefore, the temperatures permitted ina potential post-deposition anneal of the positive cathode may belimited, because for example, a chemical reaction between theelectrolyte and the positive cathode is preferably avoided, as well as areaction between the negative anode and the electrolyte.

3.2 Anode Configuration

Exemplary embodiments of “inverted configuration” have already beendescribed above.

When fabricating an embodiment containing a negative anode entirely ontop of the electrolyte, there may, for example, be no direct chemicalinteraction between the negative anode and the barrier layer.

When fabricating an embodiment of a negative anode partially on top ofthe electrolyte, the “normal configuration” (see 3.1.1) is preferable.The overhanging area of the negative anode over the electrolyte layeredge may be prevented from touching the barrier layer for the case wherethere is an anode current collector present (see FIG. 7 a). Without thepresence of an adequately configured anode current collector theoverhanging area of the negative anode may touch the barrier layer (seeFIG. 7 b). In either case, the negative anode can, for example,preferably be chemically inert to the barrier layer and its barriersublayers with which the negative anode is in direct contact, because,owing to its limited thickness and grain boundary morphology, the anodecurrent collector may not provide adequate chemical separation betweenthe negative anode and the barrier layer. In such case, the selection ofthe negative anode material determines the selection of the barriersublayer materials. In this regard, a CO₃O₄ barrier sublayer may not beused if the negative anode is a metallic lithium anode and this anodehas contact to the CO₃O₄ barrier sublayer. Otherwise, the metalliclithium can reactively degrade the CO₃O₄ barrier sublayer to Li₂O, CoO,and solid solutions of Li(Co) and Co(Li).

If the negative anode and/or its anode current collector make contact tothe barrier layer, then two cases may need to be assessed: whether thenegative anode and/or its anode current collector make contact to: 1) aninsulating barrier sublayer, or 2) an electrically conductive barriersublayer. In the first instance, it may be sufficient that this barriersublayer be chemically inert to the negative anode and/or its anodecurrent collector, such as Si₃N₄ when using a metallic lithium anode.For the second instance, in addition to the conductive barrier sublayerbeing in contact be chemically inert to the negative anode and/or itsanode current collector, a more sophisticated barrier sublayer approachmay, for example, be used for conductive substrates, for example,metallic ones and doped and undoped silicon (see examples in FIGS. 4 a-4c). For insulating polymeric substrates and the second instance, it issufficient to use a non-continuous conductive barrier sublayer so thatthe positive part and the negative part of the battery are notshort-circuited through this electrically conductive barrier sublayer.

The use of, for example, a 1 μm thick ZrN barrier sublayer is relativelysimple and effective for the embodiment where a metallic lithiumnegative anode makes contact to this ZrN barrier sublayer, which in turnshould not be shared with the positive part of the battery, but insteadthe positive part of the battery may be located over an insulatingbarrier sublayer such as Si₃N₄. One advantage of this latter exampleembodiment is that the ZrN barrier sublayer also may serve as the anodecurrent collector for the negative metallic lithium anode (see FIG. 8).

An anode current collector may comprise an inert metal, an inert alloy,or an inert nitride and thus may not be prone to reacting with thebarrier layer or the negative anode. The anode current collector shouldpreferably not make electrical contact to a conductive barrier sublayerto which also the positive cathode and/or the cathode current collectorhas electrical contact. Otherwise, the battery may be in ashort-circuited state.

3.3 Substrate in Electrical Contact with the Electrochemically ActiveCell

In an example embodiment where there is no reaction between thesubstrate and the positive cathode or the negative anode, the substratewith those electrodes may be brought into direct electrical contact orinto indirect electrical contact via a current collector. However, forconductive substrates, such as metallic substrates, doped or undopedsilicon wafers or metallized polymeric substrates, only one of thoseelectrodes may, for example, be allowed to be in electrical contact withthe substrate, because otherwise the electrochemically active cell maybe shorted out or a strong current leakage may be introduced. Thisexemplary approach has the advantage of conveniently using theconductive substrate as one of, for example, two terminals of anelectrochemical apparatus (see FIG. 9).

3.4 Double Sided Electrochemical Apparatus

The present invention may include embodiments wherein an electrochemicalapparatus has at least one electrochemically active cell on each side ofthe substrate. The fabrication, for example, of embodiments may includewherein each electrochemically active cell is deposited by a givenelectrochemically active cell component layer, such as the positivecathode, on both sides of the substrate using equipment that, forexample, is capable of depositing both sides of the substrate at thesame time prior to proceeding to the fabrication of the next batterycomponent layer, which may also be deposited on both sides of thesubstrate at the same time.

The potential sequential fabrication process of the battery componentlayers may, for example, be done in the same manner as for a singlesided electrochemical apparatus. As a result of this exemplary approachof layer completion on both sides of the substrates prior to depositingthe next layer on both sides of the substrate, a potentialpost-deposition anneal might not be applied to a layer on the other sideof the substrate that should not be subjected to such a post-depositionanneal.

Another exemplary approach may be to partially complete the fabricationof the first electrochemically active cell on the first side of thesubstrate before proceeding to the partial completion of the fabricationof the second electrochemically active cell on the second side of thesubstrate or any further electrochemically active cell on either thefirst or second side of the substrate. This approach may, for example,be employed when the available deposition equipment does not allowdouble sided depositions at the same time. For example, a deposit ontothe first side of the substrate comprising a cathode current collectorand then a positive cathode layer may be accomplished before depositinga cathode current collector and a positive cathode layer onto the secondside of the substrate. After these steps, a post-deposition anneal maybe applied to the partially completed electrochemically active cells onthis substrate at the same time prior to continuing the fabrication ofthe electrochemically active cell on the first side of the substrateusing the fabrication sequence electrolyte-anode currentcollector-anode. Subsequently, the same fabrication sequence may beapplied to the second side of the substrate before both sides areencapsulated with heat sensitive polymeric laminates on both sides ofthe substrates at the same time or thin-film encapsulations that may beapplied at the same time or sequentially.

Depending on the actual conditions of a potential post-deposition annealof the positive cathode and/or negative anode, a third approach may bepossible where the fabrication of the first electrochemically activecell on the first side of the substrate may completed prior to startingthe fabrication of the second electrochemically active cell on thesecond side of the substrate.

3.5 Protective Encapsulation or Protective Encasing Design

For the purpose of the present invention, we define “protectiveencasing” as a protective enclosure such as, for example, a pouch orhermetically sealed metal can that contains the electrochemicalapparatus, and in certain embodiments may fully enclose and/or entirelycontain the apparatus. We define “protective encapsulation” as, forexample, a protection that “caps” the electrochemical apparatus or oneor more given individual electrochemically active cells of theelectrochemical apparatus. The cap may, for example, be attached to thesubstrate area available next to the electrochemically active cell orany suitable substrate area of the electrochemical apparatus.

Before the electrochemical apparatus of the present invention may beoperated in the ambient environment, it is, for example, preferred thatit be protected against any reactive chemicals that may be present in agiven ambient environment and which may detrimentally react or degradethe electrochemical apparatus. For example, if the ambient environmentis air, the electrochemical apparatus of the present invention maypreferably be protected against moisture, among other reactive chemicalssuch as O₂ or CO₂ (see for example, U.S. Pat. No. 6,916,679 incorporatedherein in its entirety). One may protect the electrochemical apparatusof the present invention against those external, chemical factors, forexample, inside a hermetically sealed metal can with electricalfeed-throughs, such as, for example, laser welded stainless steel cansor vacuum-tight metal or glass tubes or vessels. However, the dimensionsof such kinds of protective encasings may add too much inert volume andmass to an electrochemical apparatus whose components, except for theenergy carrying positive cathode, can be minimized relative to theirthicknesses. This strategy of minimization is particularly useful forthe thickness of the inert components of the electrochemical apparatus,such as the substrate and any protective encasings, or protectiveencapsulations as well, whose mere presence is always reducing thedensities of power, energy, and capacity of any electrochemically activecell, and thus the densities of power, energy, and capacity of theelectrochemical device.

For the reasons described above, the protective encapsulation orprotective encasing should preferably be as thin as possible while stillbeing able to protect the electrochemical apparatus against a variety ofchemicals present in the ambient environment in which theelectrochemical apparatus is operated. Protection against thosechemicals includes implicitly all of the pertaining temperatures of andexposure times to said chemicals, which the electrochemical apparatusencounters during its lifetime. However, it is the sole discretion ofthe manufacturer of the electrochemical apparatus to establish theoptimum parameters of the electrochemical apparatus relative tomanufacturing costs and performance. In this regard, an electrochemicalapparatus, which may be operated only for a few days after itsfabrication, for example, may receive a potentially cheaper and lesssophisticated protective encapsulation or protective encasing than anelectrochemical apparatus that, for example, may be designed to beoperated for years.

Both protective encapsulation and protective encasing should allowexternal access to the terminals of the electrochemical apparatus. Thisexternal access may be accomplished by, for example, adopting one of thefollowing three main engineering designs. First, the substrate and/orthe protective encapsulation can serve as terminals to which directexternal contact can be made (see, for example, FIG. 3 b, substrate 300serves as the positive terminal). Second, a terminal can be rununderneath the hermetically sealed edge of the protective encapsulationand further extend outside of said protective encapsulation to whichcontact can be made (see, for example, FIG. 4 a, layers 430 and 480).Analogously, a terminal can be run through a hermetically sealed exit oropening of the protective encasing, and further extend outside of saidprotective encasing to which contact can be made (see, for example,prismatic Li-ion bulk battery technology). Third, an opening can beprovided in the protective encapsulation or protective encasing, whichallows direct external access to a terminal inside of theelectrochemical apparatus, but wherein sensitive parts, for example, themoisture sensitive electrolyte, may be separated from the ambientenvironment, for example, moisture containing air, only by the thicknessof the terminal or its adjacent current collector.

For improved lifetime, which represents a useful performance parameterof the electrochemical apparatus of the present invention, one mayensure, in particular for the case in which said opening of said thirddesign is located near the electrolyte area, that the electrolytereceives added protection by, for example, a moisture protection layer,as schematically shown in FIG. 10.

3.6 Current Collector and Terminals

Less electrically conducting electrode materials, such as a LiCoO₂positive cathode or a Li₄Ti₅O₁₂ negative anode, may need a wellconducting, inert backside contact (current collector), for example Auor Ni, in order to keep the electrical resistance of that electrodesmall, as well as minimize the ionic diffusion pathway inside theelectrode, which is accomplished when the z-parameter (thickness) of theelectronic and ionic pathway is kept to a minimum. This principle isimplemented in most batteries where the electrodes are preferably builtflat or thin (z-parameter), that is, have a length dimension(x-parameter) and width dimension (y-parameter) that is maximizedcompared to the thickness (z-parameter). Some electrodes are goodelectrical conductors, both electronically and ionically, and would notneed a current collector for the aforementioned reasons. However, theymay be chemically so reactive, such as a negative metallic Li anode,that they may preferably be separated from other battery parts, such asthe negative terminal, by an appropriate inert “bridge”, such as Ni inthe case of a negative Li metallic anode. This “bridge” may make contactto the reactive, well conducting electrode only in one corner or at oneedge, in contrast to the full-area backside contact in the case of apoorly conducting electrode. The bridge serves as an inert mediumbetween the reactive electrode and its terminal, and provides currentcollecting properties, and may thus be called “current collector” aswell.

A terminal of the electrochemical apparatus of the present inventionmay, in one embodiment, be an extended current collector, and may thusmade of the same material that makes contact to the electrode. However,the current collector used in thin-film batteries may be very thin andmechanically dense so that externally making contact to them,mechanically (e.g., clipping), soldering, or spot welding, for example,may not form a preferable permanent electrical contact. One may preferto improve the contact properties of the current collector by adding,for example, thick and/or porous, well-conducting materials to the endof the current collector, which is the area called a “terminal”, towhich a mechanical, soldered, or spot welded external electricalcontact, for example, may be accomplished. In this regard,screen-printed silver and silver alloys, about 5-15 μm thick and fairlyporous, have been successfully employed as a terminal that is printed ina manner so that the cathode or anode current collector may make goodelectrical contact to it while the screen-printed material does notchemically contaminate the electrochemically active cell, or cells, atany point during their fabrication, operation, or storage.

Example embodiments and implementations of the invention are describedwith reference to the drawings.

FIG. 1 illustrates one embodiment of an electrochemical apparatus. Thesubstrate part 100 may, for example, be chemically separated from thebattery part 120 via a barrier layer 110, which is composed of barriersublayers 111-114. Battery component layers 121-125 are provided. Apositive battery terminal 126 and a negative battery terminal 127 arefurther provided.

FIG. 2 illustrates one embodiment of an example of a barrier layer 210of the exemplary barrier sublayers 1000 Å MoSi₂ 211, 3000 Å WC 212, 4000Å Si₃N₄ 213, and 5000 Å ZrN 214. As shown, the area dimensions of thesesublayers may, for example, be very different from each other while theymay still accomplish the preferred electrical separation between thepositive part (214, 220, 230, and 240) and the negative part (260, 270,and 280) of the electrochemically active cell. The cathode currentcollector, the positive terminal, and the positive cathode arerepresented by items 220, 230, and 240, respectively. The positive partof the electrochemically active cells may include at least a positivecathode, a cathode current collector, and a positive terminal. Thecathode current collector alone may serve as a positive terminal. Thenegative anode, the anode current collector, and the negative terminalare represented by 260, 270, and 280, respectively. The negative part ofthe electrochemically active cell may include at least a negative anode,an anode current collector, and a negative terminal. An extended anodecollector may also serve as: (1) a negative terminal; (2) an anode; and(3) an anode current collector, an anode, and a negative terminal. Theelectrolyte 250 may, for example, electronically separate the positivepart from the negative part of the electrochemically active cell. Inthis particular case, the electrochemically active cell may, forexample, be protected by an encapsulation 290 with an opening 291 toaccess the negative terminal 280. This encapsulated electrochemicallyactive cell may be fabricated onto a substrate 200 which altogetherforms the electrochemical apparatus.

FIG. 3 a illustrates an example embodiment of a barrier layer 310containing a first barrier sublayer 311 and a second barrier sublayer312, which may, for example, be electrically conductive for anembodiment wherein the electrical separation between the positive partand the negative part of the electrochemically active cell isaccomplished through fabrication of the negative part entirely on top ofthe electrolyte 350. The positive part may, for example, constitute thesecond barrier sublayer 312, the cathode current collector 320, thepositive terminal 330, and the positive cathode 340. When the firstbarrier layer 311 provided is electrically conductive, the positive partmay additionally constitute the first barrier layer 311. For embodimentswhere the substrate 300 is electrically conductive, for examplemetallic, in conjunction with an electrically conductive first barrierlayer 311, then this substrate may also become a part of the positivepart. The negative part may constitute the negative anode 360, the anodecurrent collector 370, and the negative terminal 380. In this particularexample, the electrochemically active cell may be protected by anencapsulation 390 with an opening 391 to access the negative terminal380.

FIG. 3 b illustrates an example embodiment of a barrier layer 310containing a first barrier sublayer 311 and a second barrier sublayer312, which may for example be electrically conductive, for an embodimentwhere the electrical separation between the positive part and thenegative part of the electrochemically active cell may, for example, beaccomplished through fabrication of the negative part entirely on top ofthe electrolyte 350, while the cathode current collector 320, thepositive terminal 330, and the positive cathode 340 may, for example,have electrical contact to the metallic substrate 300 via the secondbarrier sublayer 312. In this configuration, the metallic substrate 300may serve as the positive terminal. The positive part may constitute ametallic substrate 300, a second barrier sublayer 312, a cathode currentcollector 320, a positive terminal 330, and a positive cathode 340. Foran embodiment wherein the first barrier layer 311 is electricallyconductive, the positive part may additionally include a first barrierlayer 311. The negative part may include a negative anode 360, an anodecurrent collector 370, and a negative terminal 380. In this particularexample, an electrochemically active cell may be protected by anencapsulation 390 with an opening 391 to access the negative terminal380.

FIG. 3 c illustrates an example embodiment of a barrier layer 310containing a first barrier sublayer 311 and a second barrier sublayer312, which may, for example, be electrically conductive, for the case inwhich the electrical separation between the positive part and thenegative part of the electrochemically active cell is accomplishedthrough fabrication of the positive part entirely on top of theelectrolyte 350 while the anode current collector 370, the negativeterminal 380, and the negative anode may, for example, have electricalcontact to the metallic substrate 300 via the second barrier layer 312.In this configuration, the substrate 300 may, for example, serve as thepositive terminal as well. The positive part may constitute the cathodecurrent collector 320, the positive terminal 330, and the positivecathode 340. The negative part may constitute metallic substrate 300,the second barrier sublayer 312, the negative anode 360, the anodecurrent collector 370, and the negative terminal 380. In the case wherethe first barrier layer 311 is electrically conductive as well, thenegative part may additionally constitute this first barrier layer 311.In this particular example, the electrochemically active cell may beprotected by an encapsulation 390 with an opening 391 to access thepositive terminal 330.

FIG. 4 a illustrates an example embodiment of a barrier layer 410containing electrically conductive barrier sublayers for the case inwhich the electrical separation between the positive and negative partof the electrochemically active cell may not be done via fabrication ofthe negative part entirely on top of the electrolyte 450. Together withthe electrolyte 450 the second barrier layer 412, which is electricallyinsulating, may, for example, separate the positive from the negativepart of the electrochemically active cell. The positive part mayconstitute a cathode current collector 420, a positive terminal 430, anda positive cathode 440. If the third barrier sublayer 413 iselectrically conductive, then it may, for example, also become a memberof the positive part. The first barrier sublayer 411 may be eitherelectrically insulating or conductive. In the latter case, it may becomea member of the negative part itself, for example, while making thesubstrate 400 a member of the negative part as well. Additionally, thenegative part may constitute the negative anode 460, the anode currentcollector 470, and the negative terminal 480. In this configuration themetallic substrate also may serve as the negative terminal. Finally, theelectrochemically active cell may be protected by an encapsulation 490.

FIG. 4 b illustrates an embodiment of another example of a barrier layer410 containing electrically conductive barrier sublayers for the case inwhich the electrical separation between the positive and negative partof the electrochemically active cell is not done via fabrication of thenegative part entirely on top of the electrolyte 450. Together with theelectrolyte 450, the second barrier layer 412, which is electricallyinsulating, may, for example, separate the positive from the negativepart of the electrochemically active cell. The positive part mayconstitute a cathode current collector 420, a positive terminal 430, anda positive cathode 440. If the third barrier sublayer 413 iselectrically conductive, then it may also become a member of thepositive part. The first barrier sublayer 411 may be either electricallyinsulating or conductive. In the latter case, it may become a member ofthe negative part while making the substrate 400 a member of thenegative part as well. Additionally, the negative part may constitutethe negative anode 460, the anode current collector 470, and thenegative terminal 480. In this configuration, the metallic substrate mayserve as the negative terminal as well. Finally, the electrochemicallyactive cell may be protected by an encapsulation 490.

FIG. 4 c illustrates an embodiment of another example of a barrier layer410 containing electrically conductive barrier sublayers for the case inwhich the electrical separation between the positive and negative partof the electrochemically active cell is not done via fabrication of thenegative part entirely on top of the electrolyte 450. The negative anode460 may, for example, have direct contact with the third barriersublayer 413, which therefore is preferred to be chemically inert tonegative anode 460. In this example, the third barrier sublayer 413 may,for example, be electrically insulating so that, together with theelectrolyte 450, it may provide the electrical separation between thepositive and the negative part of the electrochemically active cell. Thepositive part may constitute the cathode current collector 420, thepositive terminal 430, and the positive cathode 440. If the secondbarrier sublayer 412 is electrically conductive, then it also may becomea member of the positive part while also making the metallic substrate400 a member of the positive part. The first barrier sublayer 411 mayeither be electrically insulating or conductive. In the latter case, itmay also become a member of the positive part, but only if the secondbarrier layer 412 is as well. The negative part may constitute thenegative anode 460, the anode current collector 470, and the negativeterminal 480. In this configuration, the metallic substrate may serve asthe negative terminal. Finally, the electrochemically active cell may beprotected by an encapsulation 490.

FIG. 5 illustrates a graph of an X-ray diffraction (XRD) pattern of a1.6 μm thick LiCoO₂ positive cathode film fabricated onto 3000 Å goldcathode current collector over 300 Å cobalt adhesion layer over abarrier layer composed of two barrier sublayers, 5000 Å Al₂O₃ and 6000 ÅCO₃O₄, on 50 μm thick stainless steel foil type 430 substrate. TheLiCoO₂ positive cathode was post-deposition annealed at 700° C. in airfor 2 hours, which affected the underlying substrate, the barrier layerand its barrier sublayers, the cathode current collector adhesion layer,and the cathode current collector in a similar thermal manner. Therefined lattice parameters of the crystalline LiCoO₂ positive cathodefilm (a_(hex)=2.8146(4)Å; c_(hex)=14.0732(8)Å) closely match thetheoretical values (e.g., ICDD 77-1370: a_(hex)=2.815(1)Å;c_(hex)=14.05(1)Å), which indicates that the crystalline LiCoO₂ positivecathode (crystallinity for the (101) plane as estimated by the Scherrerequation: 560 Å) film did not react with any of its surroundingmaterials, including the substrate. “Au” represents a gold cathodecurrent collector. “Au+S” represents overlapping peaks of gold cathodecurrent collector and stainless steel 430 substrate foil.

FIG. 6 illustrates a graph of an X-ray diffraction (XRD) pattern of a1.6 μm thick LiCoO₂ positive cathode film fabricated onto 3000 Å goldcathode current collector over 300 Å cobalt adhesion layer over abarrier layer composed of two barrier sublayers, 5000 Å Si₃N₄ and 5000 ÅSiO₂, on 300 μm thick undoped silicon substrate. The LiCoO₂ positivecathode was post-deposition annealed at 700° C. in air for 2 hours,which affected the underlying substrate, the barrier layer and itsbarrier sublayers the cathode current collector adhesion layer, and thecathode current collector in the same thermal manner. The refinedlattice parameters of the crystalline LiCoO₂ positive cathode film(a_(hex)=2.8151(4)Å; c_(hex)=14.066(6)Å) match the theoretical valuesgiven in the literature (ICDD 77-1370: a_(hex)=2.815(1)Å;c_(hex)=14.05(1)Å), which indicates that the crystalline LiCoO₂ positivecathode (crystallinity for the (101) plane as estimated by the Scherrerequation: 1100 Å) film did not react with any of its surroundingmaterials, including the silicon substrate. “Au” represents a goldcathode current collector. The peaks of the single crystal siliconsubstrate were eliminated by the theta-2theta geometry of thediffractometer.

FIG. 7 a illustrates an embodiment of an anode configuration in whichthe negative anode 760 is not in direct contact with the barrier layer710, and thus with any of its barrier sublayers 711, 712. While thefirst barrier sublayer 711 may either be electrically insulating orconductive, the second barrier sublayer 712 should be electricallyinsulating in order to avoid electrical short-circuiting of theelectrochemical active cell and thus the electrochemical apparatus. Insuch a configuration where the negative anode 760 does not contact thebarrier layer, it does not determine the selection of the chemicalcomposition of the barrier sublayers 711, 712. The positive part of theelectrochemically cell may, for example, include cathode currentcollector 720, the positive terminal 730, and the positive cathode 740that are separated by the electrolyte 750 from the negative part, whichmay constitute the negative anode 760, the anode current collector 770,and the negative terminal 780. Finally, the electrochemically activecell may be protected by an encapsulation 790.

FIG. 7 b illustrates a schematic of an anode configuration in which thenegative anode 760 is in direct contact with the barrier layer 710, andthus with its barrier sublayer 712. While the first barrier sublayer 711may either be electrically insulating or conductive, the second barriersublayer 712 is preferably electrically insulating in order to avoidelectrical short-circuiting of the electrochemical active cell and thusthe electrochemical apparatus. In such a configuration, where thenegative anode 760 has contact with the barrier layer, it may determineat least the selection of the chemical composition of that barriersublayer 712 with which it is in contact. The positive part of theelectrochemically cell may, for example, constitute the cathode currentcollector 720, the positive terminal 730, and the positive cathode 740that are separated by the electrolyte 750 from the negative part, whichmay constitute the negative anode 760, the anode current collector 770,and the negative terminal 780. Finally, the electrochemically activecell may be protected by an encapsulation 790.

FIG. 8 illustrates an embodiment of an anode configuration in which thenegative anode 860 is in direct contact with an electrically conductiveZrN barrier sublayer 811, which is the first barrier sublayer of theelectrochemical apparatus shown and may also serve as the anode currentcollector, for example. This anode current collector and barriersublayer 811 may, for example, be chemically inert even to a reactivenegative anode 860 such as metallic lithium, if so selected for thenegative anode 860. Due to the specific geometry of barrier sublayer811, selected for the embodiment of an electrochemical apparatus shownin this figure, the second barrier sublayer 812 is preferablyelectrically insulating, such as Si₃N₄. The positive part of theelectrochemically cell may include the cathode current collector 820,the positive terminal 830, and the positive cathode 840 separated by theelectrolyte 850 from the negative part, which may constitute, forexample, the metallic substrate 800, the ZrN barrier sublayer and anodecurrent collector 811, the negative anode 860, and the negative terminal870. Finally, the electrochemically active cell may be protected by anencapsulation 880.

FIG. 9 illustrates an embodiment of a specific battery configuration inwhich the negative anode 960 may be in direct contact with the substrate900 in the case where the substrate is chemically inert to the negativeanode 960, for example. In such a case, the substrate may serve as thenegative anode current collector and the negative terminal, for example,if the substrate is sufficiently electrically conductive, as is the casefor stainless steel. The positive part of the electrochemically activecell may include, for example, the cathode current collector 920, thepositive terminal 930, the positive cathode 940, and, if electricallyconductive, the second barrier sublayer 912. The first barrier layer911, however, is preferably electrically insulating in order to avoidshort-circuiting the electrochemical apparatus to the negative part,which may include, for example, the metallic substrate 900 and thenegative anode 960.

FIG. 10 illustrates an embodiment of a specific battery configuration inwhich a moisture protection layer 1092 protects, for example, themoisture-sensitive electrolyte layer 1050 against moisture present inthe ambient environment for an embodiment where the protectiveencapsulation 1090 has been fabricated with an opening 1091 forproviding access to the negative terminal 1080. The negative terminal1080 and the anode current collector 1070, for example, may not besufficiently thick and/or moisture blocking to protect the underlyingelectrolyte layer 1050 over longer periods of time. The schematic is amodified improvement of the electrochemical apparatus shown in FIG. 3 a.The substrate 1000 may be electrically insulating or conductive, and somay be the barrier sublayers 1011 and 1012, which may constitute thebarrier layer 1010. Further components of the electrochemical apparatusshown in FIG. 10 are the cathode current collector 1020, the positiveterminal 1030, the positive cathode 1040, and the negative anode 1060.

Although the invention has been particularly shown and described withreference to the various embodiments provided above, it will beunderstood by those skilled in the art that various changes in form anddetail may be made to these various embodiments without departing fromthe spirit and scope of the invention.

1. An electrochemical apparatus comprising: a) a substrate, selectedfrom the group of a metallic, a polymeric, or a doped or undoped siliconmaterial, with a first side; b) a first electrochemically active cell onsaid first side having a negative part and a positive part, said partsfurther comprising one or more terminals; c) a first barrier layer onsaid first side which chemically separates said first electrochemicallyactive cell from said substrate; and d) wherein said first barrier layerfurther comprises a plurality of sublayers, wherein said barrier layerremains electrically conducting or semiconducting between saidelectrochemically active cell and said substrate.
 2. The electrochemicalapparatus of claim 1 further comprising a plurality of electrochemicallyactive cells provided on said first side of said substrate.
 3. Theelectrochemical apparatus of claim 1 wherein said first barrier layercomprises a chemically inert material with respect to said firstelectrochemically active cell and said substrate; and is adapted to bediffusion blocking relative to said first electrochemically active cell,and said substrate, during the fabrication of said firstelectrochemically active cell onto said substrate, and during operationand storage conditions of said electrochemical apparatus.
 4. Theelectrochemical apparatus of claim 1 wherein: a) said positive part ofsaid first electrochemically active cell is not in electrical contactwith said negative part of said first electrochemically active cell; b)said positive part of said first electrochemically active cell comprisesat least a positive cathode, a cathode current collector, and a positiveterminal; and c) said negative part of said first electrochemicallyactive cell comprises at least a negative anode, an anode currentcollector, and a negative terminal.
 5. The electrochemical apparatus ofclaim 4 wherein said cathode current collector comprises said positiveterminal.
 6. The electrochemical apparatus of claim 4 wherein said anodecurrent collector comprises said negative terminal.
 7. Theelectrochemical apparatus of claim 4 wherein said anode currentcollector comprises said anode.
 8. The electrochemical apparatus ofclaim 4 wherein said anode current collector comprises said anodecurrent collector, said anode, and said negative terminal.
 9. Theelectrochemical apparatus of claim 1 wherein said sublayers eachcomprise the same shape and area size.
 10. The electrochemical apparatusof claim 1 wherein at least one of said sublayers comprises a differentshape and area size from another of said plurality of sublayers.
 11. Theelectrochemical apparatus of claim 10 wherein at least one of saidsublayers comprises an electrically insulating material.
 12. Theelectrochemical apparatus of claim 10 wherein each of said sublayerscomprises electrically conducting or semiconducting material.
 13. Theelectrochemical apparatus of claim 1 wherein said first barrier layeronly partially covers said substrate such that at least said positivepart of said first electrochemically active cell is chemically separatedfrom said substrate.
 14. The electrochemical apparatus of claim 1wherein said first barrier layer only partially covers said substratesuch that at least said negative part of said first electrochemicallyactive cell is chemically separated from said substrate.
 15. Theelectrochemical apparatus of claim 1 wherein said first barrier layercomprises a thickness ranging from 0.01 μm to 1 mm.
 16. Theelectrochemical apparatus of claim 1 wherein said first barrier layercomprises a thickness ranging from 0.1 μm to 100 μm.
 17. Theelectrochemical apparatus of claim 1 wherein said first barrier layercomprises a thickness ranging from 0.5 μm to 5 μm.
 18. Theelectrochemical apparatus of claim 1 wherein said substrate comprises athickness within a range of 0.1 μm to 1 cm.
 19. The electrochemicalapparatus of claim 1 wherein said substrate comprises a thickness withina range of 1 μm to 1 mm.
 20. The electrochemical apparatus of claim 1wherein said substrate comprises a thickness within a range of 10 μm to100 μm.
 21. The electrochemical apparatus of claim 1 wherein saidsublayers comprise a chemical compound selected: a) from the group ofmetals, semi-metals, alloys, borides, carbides, silicides, nitrides,phosphides, oxides and iodides; b) from the group of any multinarycompounds composed of borides, carbides, silicides, nitrides,phosphides, oxides and iodides; or c) from the group of high-temperaturestable organic polymers and high-temperature stable silicones.
 22. Theelectrochemical apparatus of claim 1 wherein at least one of saidsublayers comprise a single phase of crystalline, nano-crystalline,amorphous, or glassy material or poly phase mixture or compositethereof.
 23. The electrochemical apparatus of claim 1 wherein at leastone of said sublayers comprise a single phase of amorphous or glassymaterial.
 24. The electrochemical apparatus of claim 1 wherein saidfirst electrochemically active cell comprises a battery selected fromthe group of lithium metal anode batteries, lithium-ion anode batteries,and lithium free anode batteries.
 25. The electrochemical apparatus ofclaim 24 wherein said first electrochemically active cell comprises apositive thin-film cathode deposited by vapor deposition, and wherein athickness of said positive thin-film cathode is less than 200 μm. 26.The electrochemical apparatus of claim 24 wherein said firstelectrochemically active cell comprises a positive thin-film cathodedeposited by non-vacuum deposition, and wherein a thickness of saidpositive thin-film cathode is less than 200 μm.
 27. The electrochemicalapparatus of claim 25 wherein said positive thin-film cathode comprisessingle crystallites having a size of at least 100 Å.
 28. Theelectrochemical apparatus of claim 26 wherein said positive thin-filmcathode comprises single crystallites having a size of at least 100 Å.29. The electrochemical apparatus of claim 1 wherein said firstelectrochemically active cell comprises a thin-film solid-stateelectrolyte having a thickness of less than 100 μm.
 30. Theelectrochemical apparatus of claim 1 wherein said firstelectrochemically active cell comprises a thin-film negative anodeselected from the group of lithium metal, lithium-ion anode, or a metalthat does not form inter-metallic compounds with lithium, and whereinthe thickness of said thin-film negative anode is less than 200 μm. 31.The electrochemical apparatus of claim 1 wherein said firstelectrochemically active cell further comprises a protectiveencapsulation and wherein said protective encapsulation is adapted toprotect said first electrochemically active cell against at leastmechanical and chemical factors from the ambient environment.
 32. Theelectrochemical apparatus of claim 31 wherein said encapsulation has atleast one opening adapted to allow direct electrical contact to at leastone terminal of said first electrochemically active cell.
 33. Theelectrochemical apparatus of claim 32 wherein said electrochemicallyactive cell further comprises an electrolyte and wherein said one ormore terminals are separated from said electrolyte by a moistureprotection layer.
 34. The electrochemical apparatus of claim 33 whereinsaid moisture protection layer comprises a material having moistureblocking properties, and is selected: a) from the group of metals,semi-metals, alloys, borides, carbides, diamond, diamond-like carbon,silicides, nitrides, phosphides, oxides, fluorides, chlorides, bromides,iodides; b) from the group of any multinary compounds composed ofborides, carbides, silicides. nitrides, phosphides, oxides, fluorides.chlorides, bromides, and iodides; or c) from the group ofhigh-temperature stable organic polymers and high-temperature stablesilicones.
 35. The electrochemical apparatus of claim 33 wherein saidmoisture protection layer comprises a single phase of crystalline,nano-crystalline, amorphous, or glassy material or poly phase mixture orcomposite thereof.
 36. The electrochemical apparatus of claim 1 furthercomprising a protective encasing and wherein said protective encasing isadapted to protect said electrochemical apparatus against at leastmechanical and chemical factors from the ambient environment.
 37. Theelectrochemical apparatus of claim 36 wherein said protective encasinghas at least one opening adapted to allow direct electrical contact toat least one terminal of said first electrochemical apparatus.
 38. Theelectrochemical apparatus of claim 37 wherein said electrochemicallyactive cell further comprises an electrolyte and wherein said one ormore terminals are separated from said electrolyte by a moistureprotection layer.
 39. The electrochemical apparatus of claim 38 whereinsaid moisture protection layer comprises a material having moistureblocking properties, and is selected: a) from the group of metals,semi-metals, alloys, borides, carbides, diamond, diamond-like carbon,silicides, nitrides, phosphides, oxides, fluorides, chlorides, bromides,iodides; b) from the group of any multinary compounds composed ofborides, carbides, silicides, nitrides, phosphides, oxides, fluorides,chlorides, bromides, and iodides; or c) from the group ofhigh-temperature stable organic polymers and high-temperature stablesilicones.
 40. The electrochemical apparatus of claim 38 wherein saidmoisture protection layer comprises a single phase of crystalline,nano-crystalline, amorphous, or glassy material or poly phase mixture orcomposite thereof.
 41. The electrochemical apparatus of claim 1 furthercomprising a second layer located on a second side of said substrate.42. The electrochemical apparatus of claim 41 wherein said second layercomprises a chemical compound selected: a) from the group of metals,semi-metals, alloys, borides, carbides, diamond, diamond-like carbon,silicides, nitrides, phosphides, oxides, fluorides, chlorides, bromides,iodides; b) from the group of any multinary compounds composed borides,carbides, silicides, nitrides, phosphides, oxides, fluorides, chlorides,bromides, and iodides; or c) from the group of high-temperature stableorganic polymers and high-temperature stable silicones.
 43. Theelectrochemical apparatus of claim 1 wherein at least one of saidsublayers comprises an electrically insulating material.
 44. Theelectrochemical apparatus of claim 1 wherein each of said sublayerscomprises electrically conducting or semiconducting material.